1. Field of the Invention
The present invention relates to a highly uniform spandex and to a process for making such spandex using specific ingredients. More particularly, the polyurethaneurea of which such spandex is comprised has both alkylurethane and monoalkylurea ends, and such ingredients include selected aliphatic primary monoalcohols and aliphatic primary monoamines.
2. Description of Background Art
A variety of polyurethaneurea compositions useful for making spandex are disclosed in U.S. Pat. Nos. 3,994,881; 5,948,875; 5,981,686; 4,871,818; 4,973,647; 5,000,899 and Japanese Published Patent Application JP08-020625. U.S. Pat. No. 5,589,563 discloses the use of surface modifying endgroups, particularly for biomedical polymers. Monofunctional chain terminators are disclosed in U.S. Pat. Nos. 3,384,623; 3,184,426; 5,032,664; British Patent GB 1102819; Japanese Published Patent Applications JP7-278246; JP2000-103831; and JP02-51518 and International Application WO99/62979. British Patents GB1153739; GB118737; and GB1118735 disclose the use of acid and acid-generating compounds in the manufacture of elastic polyurethane filaments.
However, none of the prior art disclosures make possible sufficiently uniform spandex or adequate spandex spinning continuity, and improvements in spandex uniformity and in processes to make spandex are still needed.
The invention provides a spandex comprising a polyurethaneurea which is the reaction product of:
a) a capped glycol comprising the reaction product of:
i) a polymeric glycol selected from the group consisting of polyether glycols, polyester glycols, and polycarbonate glycols;
ii) a diisocyanate; and
iii) an aliphatic primary monoalcohol comprising 1-10 carbons;
b) an aliphatic diamine chain extender comprising 2-12 carbons; and
c) a primary aliphatic monoamine chain terminator comprising 5-12 carbons;
wherein:
the polyurethaneurea has:
monoalkylurea ends and alkylurethane ends;
a ratio of monoalkylurea ends to alkylurethane ends of at least about 0.5:1; and
a ratio of monoalkylurea ends to alkyurethane ends of at most about 10: 1; and wherein the spandex has a coefficient of denier variation which is lower by at least about 15% than that of spandex comprising an otherwise identical polyurethaneurea having dialkylurea and amine ends.
The invention also provides a process for making spandex comprising the steps of:
a) providing a polymeric glycol selected from the group consisting of polyether glycols, polyester glycols, and polycarbonate glycols;
b) providing a diisocyanate;
c) providing an aliphatic primary monoalcohol comprising 1-10 carbons;
d) contacting the glycol, diisocyanate, and monoalcohol to form a capped glycol;
e) providing an aliphatic diamine chain extender comprising 2-12 carbons;
f) providing primary aliphatic monoamine chain terminator comprising 5-12 carbons;
g) contacting the capped glycol, the diamine, and the monoamine in a solvent to form a polyurethaneurea solution; and
h) spinning the polyurethaneurea solution to form the spandex,
wherein:
a mole ratio of monoamine to monoalcohol is at least about 0.5:1; and
a mole ratio of monoamine to monoalcohol is at most about 10:1.
It has now been found that spandex comprising a polyurethaneurea having alkylurethane and monoalkylurea chain ends at certain ratios has unexpectedly high uniformity. It has also been found that certain combinations of selected aliphatic monoalcohols and aliphatic monoamines, when used in making a polyurethaneurea to be spun into spandex, provide unexpected process advantages.
As used herein, xe2x80x98spandexxe2x80x99 means a manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer comprised of at least 85% by weight of a segmented polyurethane. Polyurethaneureas constitute a subgroup of polyurethanes. xe2x80x9cPrimaryxe2x80x9d amine or alcohol means that the amino or hydroxyl group is covalently bonded to a carbon which is in turn covalently bonded to at most one other carbon.
Polyurethaneureas which have been chain-terminated with an aliphatic monoalcohol have alkylurethane ends, and those that have been chain-terminated with an aliphatic primary amine have monoalkylurea ends. Chain termination with (secondary) dialkylamines gives dialkyl urea ends. Amine ends in the polyurethaneurea are derived from incompletely reacted diamine chain extender.
The spandex of the invention comprises a polyurethaneurea having a ratio of monoalkylurea ends to alkylurethane ends of at least about 0.5:1 and at most about 10:1. When the ratio is outside the indicated range, the spandex has low denier (decitex) uniformity. The polyurethaneurea can have at least about 5 meq/kg and at most about 30 meq/kg alkylurethane ends. The polyurethaneurea can have at least about 2 meq/kg monoalkylurea ends and at most about 55 meq/kg monoalkylurea ends, based on polyurethaneurea weight. The polyurethaneurea can have up to about 50 meq/kg amine ends, based on polyurethaneurea weight. The values herein for the various types of polyurethaneurea chain ends include consideration of unreactive ends in the polymeric glycol, which generally amount to less than about 10 meq/kg, based on total ingredients weight or polyurethaneurea weight, as circumstances dictate.
Further, the spandex has a coefficient of denier variation which is lower, by at least about 15% and preferably at least about 25%, than that of spandex comprising an otherwise identical polyurethaneurea having dialkylurea and amine ends. Such a reduction in coefficient of denier variation is significant. Preferably, the spandex has a coefficient of denier variation of at most about 15.
The polyurethaneurea constituent of the spandex of the invention is the reaction product of a) a capped glycol made from a polymeric glycol selected from the group consisting of polyether glycols, polyester glycols, and polycarbonate glycols, a diisocyanate, and an aliphatic primary monoalcohol comprising 1-10 carbons; b) an aliphatic diamine chain extender comprising 2-12 carbons; and c) a primary aliphatic monoamine chain terminator comprising 5-12 carbons.
The process of the present invention comprises contacting a polymeric glycol, an aliphatic primary monoalcohol, and a diisocyanate to form a capped glycol, contacting the capped glycol with an aliphatic diamine chain extender and an aliphatic primary monoamine chain terminator in a solvent, and wet- or dry-spinning the resulting solution of polyurethaneurea to form the spandex. The mole ratio of monoamine to monoalcohol is at least about 0.5:1 and at most about 10:1. When the ratio is too high, the monoalcohol has little effect, and when it is too low, the polyurethaneurea can become insufficiently soluble in the spinning solvent.
Polymeric glycols suitable for use in making the polyurethaneurea of which the spandex of the invention is comprised and in the process of the invention can have number average molecular weights of approximately 1500-4000 daltons and include polyether glycols (for example poly(tetramethyleneether) glycol which can have a molecular weight of 1500-2500 daltons and poly(tetramethyleneether-co-2-methyltetramethyleneether) glycol which can have a weight of 2000-4000 daltons), polycarbonate glycols (for example poly(pentane-1,5-carbonate) glycol and poly(hexane-1,6-carbonate) glycol), and polyester glycols (for example poly(2,2-dimethyl-1,3-propane dodecanedioate) glycol, poly(ethylene-co-1,2-propylene adipate) glycol, poly(hexamethylene-co-2,2-dimethyltrimethylene adipate) glycol, and poly(ethylene-co-butylene adipate) glycol). If desired, poly(2,2-dimethyl-1,3-propane dodecanedioate) glycol can be short-path distilled in one or more steps at reduced pressures and elevated temperatures before being capped with diisocyanate. When poly(tetramethyleneether-co-2-methyltetramethyleneether) glycol is used, the 2-methyltetramethyleneether moiety can be present in a range of approximately 4-20 mol %, based on the total ether moieties in the glycol. Such a copolyether can be prepared by copolymerization of tetrahydrofuran and 3-methyltetrahydrofuran. When poly(ethylene-co-butylene adipate) is used, the ethylene/butylene ratio can be about 50/50 to 70/30, preferably about 60/40.
The primary aliphatic monoalcohol used in making the polyurethaneurea for the spandex of the invention and in the process of the invention comprises 1-10 carbons, preferably 4-7 carbons. Examples of useful monoalcohols include methanol, ethanol, n-butanol, n-hexanol, n-octanol, n-decanol, and mixtures thereof. The monoalcohol can be used in the process at an amount of at least about 5 meq/kg and at most about 30 meq/kg, based on total ingredients. When the amount is too low, the monoalcohol has little effect, and when it is too high, the polyurethaneurea solubility can suffer.
The diisocyanate can be 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, 1,6-diisocyanatohexane, toluene diisocyanate, 1-isocyanato-4-[(4xe2x80x2-isocyanatophenyl)methyl]benzene, 2,2-bis(4-socyanatophenyl)-propane, 1,1xe2x80x2-methylenebis(4-isocyanatocyclohexane), 1,4-diisocyanato-cyclohexane, 1,4-bis(4-isocyanato-alpha,alpha-imethylbenzyl)benzene, 1-isocyanato-2-[(4xe2x80x2-isocyanato-phenyl)methyl]benzene, and mixtures thereof. xe2x80x9cSubstantially 1-isocyanato-4-[(4xe2x80x2-isocyanatophenyl)methyl]benzenexe2x80x9d means that up to about 3 mole percent of the diisocyanate can be isomers of 1-isocyanato-4-[(4xe2x80x2-isocyanatophenyl)methyl]benzene. Generally, the NCO moiety content in the capped glycol can be about 2 to 6 weight percent, based on capped glycol. When mixtures of 1-isocyanato-4-[(4xe2x80x2-isocyanatophenyl)methyl]-benzene with 1-isocyanato-2-[(4xe2x80x2-isocyanatophenyl)methyl]benzene are used, the 1-isocyanato-2-[(4xe2x80x2-isocyanatophenyl)-methyl]benzene can be present at about 2 to 55 mole percent, preferably about 5 to 30 mol %, based on total diisocyanate, and the NCO moiety in the capped glycol can be present at about 2.0 to 3.5 wt %. Aromatic diisocyanates such as 1-isocyanato-4-[(4xe2x80x2-isocyanatophenyl)methyl]-benzene and mixtures thereof with 1-isocyanato-2-[(4xe2x80x2-isocyanatophenyl)methyl]-benzene are preferred.
In the process of the invention, the capped glycol can be dissolved in a suitable solvent, for example dimethylacetamide (xe2x80x9cDMAcxe2x80x9d), N-methylpyrrolidone, or dimethylformamide. Optionally, the capping step can be carried out in a solvent, for example dimethylacetamide containing less than about 50 ppm water and less than about 2000 ppm combined formamides and amines, based on solvent weight.
In the process of the invention, the capped glycol is contacted in a solvent with a diamine chain extender and a primary aliphatic monoamine chain terminator to form the polyurethaneurea in solution, which solution is then wet- or dry-spun to form the spandex. The diamine used to make the polyurethaneurea for the spandex of the invention and in the process of the invention comprises 2-12 carbons and can be for example ethylene diamine, 1,3-butanediamine, 1,4-butanediamine, 1,3-diamino-2,2-dimethylbutane, 1,6-hexane-diamine, 1,2-propanediamine, 1,3-propanediamine, N-methylaminobis(3-propyl-amine) 2-methyl-1,5-pentanediamine, 1,5-diaminopentane, 1,3-diamino-4-methylcyclohexane, 1,3-cyclohexanediamine, 1,1xe2x80x2-methylene-bis(4,4xe2x80x2-diaminohexane), 3-minomethyl-3,5,5-trimethylcyclohexane, 1,3-diaminopentane, and mixtures thereof. Diamines other than ethylene diamine are generally considered xe2x80x98coextendersxe2x80x99 and can be used with ethylene diamine in mounts of up to about 20 mole percent, for example in amounts of about 10 to 20 mol %, or in amounts of at most about 10 mole percent of total chain extender, but such diamines can also comprise about 50 mole percent or more of chain extender mixtures, as disclosed in U.S. Pat. Nos. 5,948,875 and 5,981,686. At xe2x80x98coextenderxe2x80x99 amounts above about 50 mole percent, when the polymeric glycol is poly(tetramethyleneether) glycol, the NCO content of the capped glycol can be about 2.5 to 6.0 wt %, and when the polymeric glycol is poly(tetramethylene-co-2-methyltetramethyleneether) glycol, the NCO content of the capped glycol can be about 2.0 to 5.5 wt %, based on capped glycol weight.
The primary monoamine chain terminator used to make the polyurethaneurea for the spandex and in the process of the invention comprises 5-12 carbons, preferably 6-7 carbons, for example n-pentylamine, n-hexylamine, cyclohexylamine, n-heptylamine, methylcyclohexylamines (for example 1-amino-3-methylcylohexane, 1-amino-2-methylcyclohexane, and 1-amino-3,3,5-trimethylcyclohexane), n-dodecylamine, 2-aminonorbornane, 1-adamantanamine, and mixtures thereof. Acyclic and monocyclic amines are preferred, due to their greater efficacy. The monoamine can be used in an amount of at least about 2 meq/kg and at most about 55 meq/kg, based on total ingredients.
The intrinsic viscosity of the polyurethaneurea of which the spandex is comprised and which is prepared and spun in the process of the invention can be about 0.90 to 1.20 dl/g, typically 0.95 to 1.10 dl/g.
Optionally, the polymeric glycol can contain acids and acid-producing compounds, which can be added before the capping step, for example phosphoric acid, benzenesulfonic acid, p-toluenesulfonic acid, sulfuric acid, carboxylic acid chlorides and anhydrides as well as phosphoric acid esters, and the like. The acid or acid-producing compound can be used in an amount of at least about 10 and at most about 125 parts per million (xe2x80x9cppmxe2x80x9d) based on polymeric glycol weight. Phosphoric acid is preferred due to its low corrosivity.
A variety of other additives can also be used in the spandex and the process of the invention, provided they do not detract from its beneficial aspects. Examples include delustrants such as titanium dioxide; stabilizers such as hydrotalcite, mixtures of huntite and hydromagnesite (for example at 0.25 to 1.0 weight percent based on polyurethaneurea), barium sulfate, hindered amine light stabilizers, UV screeners, hindered phenols, and zinc oxide; dyes and dye enhancers; and the like.
Diethylenetriamine can be used, in the chain extension step, at low levels for solution viscosity control, provided the advantages of the invention are not compromised, and in the Examples, 0-125 ppm (based on weight of polymer) were variously used.
In the Examples, polyurethaneurea solution viscosity was determined in accordance with the general method of ASTM D1343-69 with a Model DV-8 Falling Ball Viscometer (Duratech Corp., Waynesboro, Va.), operated at 40xc2x0 C. and is reported in poise. The highest solution viscosity that could be measured with this instrument was 35,000 poise.
To measure coefficient of denier variation (xe2x80x98CDVxe2x80x99), the first 50 meters of fiber at the surface of a wound spandex package were removed so that inaccuracies resulting from handling damage were avoided. Spandex was then removed for 130 seconds from the package using a rolling take-off and fed across a tensiometer comprising a piezoelectric ceramic pin. The take-up roll""s circumference was 50% greater than the feed roll""s circumference, and the feed and take-up rolls rotated at the same rpm, so that the polyurethane fiber was stretched to 50% elongation across the tensiometer. The tensiometer measured the tension as the spandex was fed through the rolls. The standard deviation of the tension was divided by the average tension to obtain the coefficient of variation, which was reported as CDV, since denier is directly proportional to the tension. CDV is independent of the linear density units used (denier vs. decitex), and low CDV indicates high fiber uniformity.
The total isocyanate moiety content of the capped glycol (weight percent NCO) was measured by the method of S. Siggia, xe2x80x9cQuantitative Organic Analysis via Functional Groupxe2x80x9d, 3rd Edition, Wiley and Sons, New York, pp. 559-561 (1963).
The strength and elastic properties of the spandex were measured in accordance with the general method of ASTM D2731-72. Three filaments, a 2-inch (5-cm) gauge length and a zero-to-300% elongation cycle were used for each of the measurements. The samples were cycled five times at a constant elongation rate of 50 cm per minute using an Instron tensile tester. Load power (xe2x80x9cLPxe2x80x9d), the stress on the spandex during initial extension, was measured on the first cycle at 200% extension. Unload power (xe2x80x9cUPxe2x80x9d) was measured at an extension of 200% on the fifth unload cycle. Percent elongation at break (xe2x80x9c%Exe2x80x9d) and tenacity at break (xe2x80x9cTxe2x80x9d) were measured on a sixth extension. Tenacity at break, load power and unload power were reported in deciNewtons per tex. Percent set was also measured on samples that have been subjected to five 0-300% elongation/relaxation cycles. The percent set (xe2x80x9c% Sxe2x80x9d) was calculated as % S=100(Lfxe2x88x92Lo)/Lo, wherein Lo and Lf are respectively the filament (yarn) length, when held straight without tension, before and after the five elongation/relaxation cycles.
Intrinsic viscosity (xe2x80x9cIVxe2x80x9d) of the polyurethaneurea was determined by comparing the viscosity of a dilute solution of the polymer in DMAc to that of DMAc itself at 25xc2x0 C. (xe2x80x9crelative viscosityxe2x80x9d method) in a standard Cannon-Fenske viscometer tube according to ASTM D2515 and is reported as dl/g.
In the Tables, xe2x80x9cComp.xe2x80x9d indicates a comparison example, not of the invention. xe2x80x9cMeq/kgxe2x80x9d refers to milliequivalents of the stated type of ingredient per kilogram of total ingredients.